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Publication numberUS3868754 A
Publication typeGrant
Publication dateMar 4, 1975
Filing dateDec 14, 1973
Priority dateSep 21, 1973
Publication numberUS 3868754 A, US 3868754A, US-A-3868754, US3868754 A, US3868754A
InventorsHatsuo Kawano
Original AssigneeHatsuo Kawano
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of manufacturing a finned-tube heat exchanger
US 3868754 A
Abstract
A method for manufacturing a finned tube as a heat exchanger. A thin-walled pipe of aluminum is used to cover the tube proper and cold working is employed instead of conventional shrink fitting of the tube to a cylindrical member on which fins are arranged. The method makes it possible to reduce the size and weight of fins, makes the fitting closer and prevents the generation of oxide layers inside the cylindrical member.
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Description  (OCR text may contain errors)

United States Patent [1 1 Kawano [11] 3,868,754 [451' Mar. 4, 1975 1 METHOD OF MANUFACTURING A FlNNED-TUBE HEAT EXCHANGER [76] Inventor: Hatsuo Kawano, No. 3330, Kagata,

Kawachinagano-shi, Osaka-fu, Japan [22] Filed: Dec. 14,1973

[21] Appl. No: 424,722

[30] Foreign Application Priority Data Sept. 21. 1973 Japan 48-10763 [52] U.S. Cl 29/l57.3 A, 29/157.3 V, 29/458, 29/523 [51] Int. Cl BZld 53/02, 1323p 15/26 [58] Field of Search 29/157.3 A, 157.3 V, 458,

[56] References Cited UNITED STATES PATENTS 1,494,128 5/1924 Primrose 29/1573 A 1,741,217 12/1929 Winslow .-29/157.4 X 1,952,896 3/1934 Rudorff 165/180 2,064,461 12/1936 Chilton et a1. 165/133 X 2,396,730 3/1946 Whitfield 29/1573 A 3.185.756 5/1965 Allison 29/l57.3 B 3,467,180 9/1969 Pensotti 29/1573 A FOREIGN PATENTS OR APPLlCATlONS 850,058 9/1960 Great Britain 29/1573 A Primary E.\'aminerC. W. Lanham Assistant Examiner-D. C. Reiley, I11 Attorney, Agent, or FirmGeorge B. Oujevolk 1 ABSTRACT A method for manufacturing a finned tube as a heat exchanger. A thin-walled pipe of aluminum is used to cover the tube proper and cold working is employed insteadof conventional shrink fitting 'of the tube to a cylindrical member on which fins are arranged. The method makes it possible to reduce the size and weight of fins, makes the fitting closer and prevents the generation of oxide layers inside the cylindrical member.

2 Claims, 2 Drawing Figures METHOD OF MANUFACTURING FlNNED-TUBE HEAT EXCHANGER The present invention relates to a method of manufacturing a finned tube for use as a heat exchanger and more particularly to the manufacturing of a finned tube having a thin-walled'pipe made of aluminium covering the tube proper.

The finned tube, conventionally used for recovering thermal energy from a'high temperature waste gas prior to its discharge from boilers, heating furnaces and the like, usually comprises a tube made of steel and fins arranged on a cylindrical member which covers the tube proper, both the cylindrical member and the fins being made of cast iron, said metals being resistant against to fitting to the exterior periphery of the tube proper.

The cylindrical member then shrinks as it cools off after fitting to the exterior periphery of the tube proper, the contact between the cylindrical member and the tube gets closer as the result. Also, this shrink fitting method is liable to cause the generation of oxide layers inside the cylindrical member which results in the increase of heat resistance at the contact region between the tube proper and the cylindrical member leading to a decrease in the heat transmitting efficiency of the finned tube.

The main object of the present invention is to correct the defects of conventional finned tubes as described by providing a method for manufacturing a finned tube which is highly effective for thermal transmitting, said method comprising covering a steel tube with a thinwalled pipe made of aluminium, said metal being characterized by softness, high thermal expansion coefficient and good heat conductivity. Fitting thereon a cylindrical member on which fins are arranged, both the cylindricalmember and the fins being made of cast iron, allowing a thorough adhesion of the thin-wall pipe covering the tube proper to the inside surface of the cylindrical member by way of cold working which expands the tube proper beginning with the expansion of diameter therein, so as to obtain perfect contact between the thin-wall tube covering the tube proper and the cylindrical member thus giving an excellent heat conductivity or heat exchanging capacity to the produced finned tube.

A preferred embodiment for the invention is described herein taken together with the annexed drawing in which:

FIG. 1 shows a partially-cutaway elevational view of the finned tube in the present invention.

FIG. 2 shows a, partially magnified sectional view of the finned tube in the present invention.

In FIGS. l and 2, numeral 11 designates the tube proper made of steel, outer periphery which is covered with a thin-wall pipe 12 made of alminium having high thermal expansion coefficient, good heat conductivity and softness.

Numeral 13 designates a number of fins side by side at a fixed interval on the outer periphery of the cylindrical member 14, the cylindrical member 14 being 2 fixed on the afore-mentioned thin-wall pipe 12 which covers the tube proper 11.

When the tube proper 11 is lengthy enough for the cylindrical member 14 to be divided into several partitions, all the partitions are connected with each other by means of a projecting annulus l5 inside one partition on one side thereof and an annular recess 16 inside the other partition also on one side thereof so that the projecting annulus 15 may be inserted fittingly into the annular recess 16 so as to firmly connect the two partitions with each other, a similar method being applied to each succeeding portion one by one to bring the rest of the partitions together as with said two partitions into perfect unity. In this case, an annular packing 18 made of alminium, lead and the like having softness, and heat resistability is provided in the annular recess 16 to prevent possible infiltration of gas and the like through the joint of partitions. An annular groove 17 is also formed on the sides of partitions so that one groove of one partition may contact with the other groove of the adjoining partition as in the case of said projecting annulus 15 and annular recess 16, said grooves playing the role of adding closeness to the connection of said partitions with each other.

In FIG. 1, numeral 19 designates another annular projection formed inside the cylindrical member 14 at one end thereof and'numeral 20 designates a space provided between said annular projection 19 and one end of the thin-wall pipe 12.

A space is provided between the outer periphery of the thin-wall pipe 12 covering the tube properll and the interior periphery of the cylindrical member 14 to allow for the expansion of the tube proper.

The finned tube of the present invention is assembled as follows:

Cover the tube proper 11 with the thin-wall pipe 12 ,on which the cylindrical member 14 as the base of said fins is fitted, thence expand the tube proper 11 internallyby'way of letting a die therethrough thereby letting the tube proper 11 press upon the interior surface of the thin-wall pipe 12. The thin-wall pipe 12 expanding as the result makes a forced contact with the interior surface of the cylindrical member 14 at the base of the fins.

In this process, the character of the thin-wall pipe -12 made of soft metal as afore-mentioned is advantageous for making the contact closer. Another character of the thin-wall pipe 12 is that it is high in heating expansion coefficient which also adds to the adhesiveness of the thin-wall pipe 12 incontacting with the tube proper ll and also with the cylindrical member 14.

The generation of oxide layers as in case of shrink fitting as mentioned hereinbefore will be prevented in the cold working method adopted in the present invention.

The finned tube-manufacturing method in the present invention also is advantageous because there are no problem for the size of fins except that the size of fins is to be decided only in relation with the mechanical durability of the fins. The shrink fitting in the conventional method needs a larger thermal area and accordingly it is necessary to make fins as large as possible.

What is claimed is:

1. A method for manufacturing a finned tube as a heat exchanger comprising the steps of: providing as an inner tube a tube which is made of steel; covering said inner tube with a thin-walled pipe made of aluminum having the properties of softness, high heating expan- 2. The method as claimed in claim 1 including disposing a plurality of outer cylindrical tubes in side by side i I relationship each member having formed therein an annular projection on one side and a space to receive said projection on the other side, the projections being fitted into the corresponding spaces.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1494128 *Jun 11, 1921May 13, 1924Power Specialty CoMethod and apparatus for expanding tubes
US1741217 *Oct 29, 1921Dec 31, 1929Foster Wheeler CorpSuperheater tube and method of making same
US1952896 *Apr 28, 1932Mar 27, 1934Superheater Co LtdTubular member for heat exchangers
US2064461 *Mar 17, 1936Dec 15, 1936Reed Propeller Co IncCylinder fin construction
US2396730 *Oct 24, 1941Mar 19, 1946Al Fin CorpCoating metal
US3185756 *May 2, 1960May 25, 1965Cool Fin Electronics CorpHeat-dissipating tube shield
US3467180 *Mar 30, 1966Sep 16, 1969Franco PensottiMethod of making a composite heat-exchanger tube
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4337824 *Oct 24, 1980Jul 6, 1982AmtrolDouble wall heat exchanger
US4546819 *Feb 10, 1984Oct 15, 1985Amtrol Inc.Double wall heat exchanger
US5461766 *Jan 26, 1994Oct 31, 1995Sun Microsystems, Inc.Method for integrally packaging an integrated circuit with a heat transfer apparatus
US5637921 *Apr 21, 1995Jun 10, 1997Sun Microsystems, Inc.Sub-ambient temperature electronic package
US5815921 *May 5, 1997Oct 6, 1998Sun Microsystems, Inc.Electronic package cooling system and heat sink with heat transfer assembly
US6029742 *Jun 3, 1997Feb 29, 2000Sun Microsystems, Inc.Heat exchanger for electronic equipment
US6446336 *Sep 3, 1999Sep 10, 2002Sunpower, Inc.Heat exchanger and method of constructing same
US20070266714 *May 17, 2007Nov 22, 2007Andreas FiedlerHeat exchanger assembly
CN100533044COct 27, 2006Aug 26, 2009谷长贵Vertical case column wing section bar for heat radiator and method for manufacturing same
EP0123923A1 *Mar 30, 1984Nov 7, 1984Zaklady Urzadzen Chemicznych METALCHEM im. Wladyslawa PlanetorzaA method of drawing ribs on tubes
WO2001018473A1 *Aug 3, 2000Mar 15, 2001Sunpower, Inc.Heat exchanger and method of constructing same
Classifications
U.S. Classification29/890.46, 29/523, 29/458
International ClassificationF28F1/30, B21C37/15, B21C37/20
Cooperative ClassificationF28F21/084, B21C37/205, F28F1/30, F28F21/082, B21C37/154
European ClassificationF28F21/08A4, F28F21/08A2, F28F1/30, B21C37/15D, B21C37/20C